why are we always tired, do you know? Firstly if we can't sleep w 1 ,we will be tired．But we are often too b 2 ．we can't f 3 our work in the day and we must do it at n 4 ．we go to bed l 5 and get up e 6 ．so we can't sleep well．Most people need at 1east eight hours and some more．If we sleep for only five or six hours a night, we will be tired．Secondly, when we are ill we will be t 7 ．But we don't know we are ill．so if you are always tired, perhaps you are not so h 8 ．You'd better go to see a doctor．Thirdly, perhaps you can't eat some kinds of food like eggs, nuts, meat, chocolate or coffee．If you are ill and tired after eating some food, please don't eat it a 9 longer．But please eat more if you are well．At last, if the air around you isn't nice and clean，you will feel tired．So please open your w 10 often or go out for a walk and you will feel better．
参考答案：
1.well 2.busy 3.finish 4.night 5.1ate 6.early 7.tired 8.healthy 9.any 10.window/windows